HVAC Efficiency Calculator Formula

Understand the math behind the hvac efficiency calculator. Each variable explained with a worked example.

Use the HVAC Efficiency Calculator

Formulas Used

Annual Cooling Savings

savings = annual_savings

Efficiency Improvement

savings_pct = (1 - old_seer / new_seer) * 100

Payback Period

payback = upgrade_cost / annual_savings

New Annual Cooling Cost

new_cost = new_cooling_cost

Variables

VariableDescriptionDefault
annual_cooling_costAnnual Cooling Cost(USD)800
old_seerCurrent AC SEER Rating(SEER)10
new_seerNew AC SEER Rating(SEER)18
upgrade_costHVAC Upgrade Cost(USD)6000
new_cooling_costDerived value= annual_cooling_cost * old_seer / new_seercalculated
annual_savingsDerived value= annual_cooling_cost - new_cooling_costcalculated

How It Works

How to Calculate HVAC Efficiency Savings

HVAC efficiency ratings tell you how much cooling or heating you get per unit of energy.

Key Ratings

  • SEER (cooling): Higher is better. Minimum is 14-15, high-efficiency is 18-25+
  • AFUE (gas heating): Percentage of fuel converted to heat. 80% to 98%
  • HSPF (heat pump heating): Higher is better. 8-13

    • Formula

    New Cost = Old Cost * (Old SEER / New SEER)

    Savings = Old Cost - New Cost

    Worked Example

    Upgrade from SEER 10 to SEER 18 AC with $800/year cooling costs and $6,000 upgrade cost.

    annual_cooling_cost = 800old_seer = 10new_seer = 18upgrade_cost = 6000
    1. 01New cooling cost: $800 * 10/18 = $444
    2. 02Annual savings: $800 - $444 = $356
    3. 03Efficiency improvement: (1 - 10/18) * 100 = 44.4%
    4. 04Payback: $6,000 / $356 = 16.9 years

    Ready to run the numbers?

    Open HVAC Efficiency Calculator